The present invention relates generally to space vehicle separation systems and, in particular, to a separation system employing an interface xe2x80x98nodexe2x80x99 between a deployable space vehicle and a space launch vehicle. The invention provides a standardized interface for space vehicles thereby reducing, or substantially eliminating, interface integration efforts between the space vehicle and launch vehicle builders. The invention also provides improved structural response characteristics under applied loading when compared to other interface designs.
Separation systems are used in a variety of contexts to provide controlled deployment of a deployable unit from a support structure. For example, in aerospace applications, separation systems are used in the space launch business to attach a space vehicle (i.e. spacecraft or satellite) to, and deploy from, a launch vehicle. They may also be used to deploy solar panels, scientific equipment, or other units from a stowed position on the space vehicle. Other possible applications of separation systems include, for example, aircraft ejection seat release, parachute actuation, and other applications involving controlled separation of two surfaces or structures. It will thus be appreciated that separation and associated deployment may involve complete detachment of the deployable unit from the support structure or movement from a non-deployed position to a deployed position. Although the present invention has been developed primarily for use in attaching a space vehicle to a space launch vehicle, it is apparent that further applications and adaptations of the invention are possible.
Generally, the interface between the space vehicle and the launch vehicle is defined by abutting interface surfaces between the two. The separation system typically includes one or more release assemblies that hold the spacecraft and launch vehicle together until the desired time of release. At the desired time of release, the separation system detaches, or disengages, releasing the space vehicle from the launch vehicle. Common separation systems include pyrotechnically actuated clamp-bands, separation nuts, and separation bolts. The present invention is intended for use where an interface incorporates a separation nut or bolt. These types of interfaces can incorporate any number of release mechanisms, typically the same type and size. This type of interface is sometimes referred to as a xe2x80x98hard-pointxe2x80x99 or xe2x80x98nodexe2x80x99 interface.
The interface between a space vehicle and a launch vehicle must be capable of transferring loads between the two structures. These loads can include vibration, acceleration, thermal, and static loads. For this reason, features of the interface must be tightly controlled with respect to tolerances associated with machining or forming processes. The longitudinal loads acting along the primary axis of the launch vehicle (i.e. the axis parallel to the primary vector of travel) are reacted by the separation bolt and bearing surfaces between the two structures. The shear loads, or side loads (those normal to the longitudinal loads), are reacted by shear pins or lips.
Because the interface features of a space vehicle and launch vehicle are generally controlled by separate manufacturers or groups within an organization, extensive integration efforts are required to ensure compatibility between the two pieces of hardware. In addition, typically a space vehicle will not be fit checked with a launch vehicle until both are nearly fully assembled. Moreover, it may be required that a space vehicle be compatible with several launch vehicles from the same manufacturer or different manufacturers. As a result, existing separation systems and associated interface configurations entail significant risk associated with new unit development, complicated integration efforts, and limited system interchangability. Furthermore, historically, each unique space vehicle has incorporated a unique, and often dramatically different, node design for the launch vehicle interface. The present invention is an attempt to provide a standardized node design.
The present invention is directed to a novel interface structure for interfacing a space vehicle or other deployable unit and a launch vehicle or other support structure, and to an associated separation system. The invention allows for interfacing the space vehicle and launch vehicle via an intermediate node that preferably incorporates both the separation system and structural interface functions. In this manner, the space vehicle and launch vehicle can be interfaced without extensive integration of the associated designs. Such an interface structure lends itself to standardization so as to mitigate risk associated with new support structure and/or deployable unit development, streamlines integration efforts, and provides a unique capability with widespread application.
The present invention incorporates the complex interface features within the system itself while providing an easily controlled interface to both the space vehicle and launch vehicle. The tightly controlled load carrying features are internal to the xe2x80x98nodexe2x80x99 while simple bolt hole patterns, controlled by common tooling, provide easy to produce interfaces to the two vehicles. The load carrying features can be verified at the node component level while bolt hole patterns are verified through xe2x80x98matchedxe2x80x99 tooling. This virtually eliminates any concerns of mismatch between the two vehicles.
According to one aspect of the present invention, an interface apparatus is provided for selectively connecting a deployable unit such as a space vehicle and a support structure such as a launch vehicle. The deployable unit includes a first interface surface and the support structure includes a second interface surface wherein, prior to deployment, the first and second interface surfaces are disposed in opposing relationship to define an interface. As set forth below, the interface surfaces need not be abutting. The deployable unit is deployable from an undeployed state where the first and second interface surfaces are proximate to one another in a deployed state wherein the interface surfaces are separated. The interface apparatus includes a support structure node member, interconnected to the support structure including a first contact surface and a deployable unit node member, interconnected to the deployable unit including a second contact surface. The first and second contact surfaces are disposed in an abutting relationship when the deployable unit is in the undeployed state so as to define a separation plane. The separation plane is located at the interface and separated from at least one of the first and second interface surfaces such that the support structure node member and deployable unit node member provide an interface structure, thereby reducing first and second interface surface design integration.
Preferably, the support structure node member and the deployable unit node member are configured so that the interface surfaces of the support structure and deployable unit are separated. In this manner, the need to integrate the support structure and deployable unit designs can be reduced or substantially eliminated. Such separation can be achieved with a variety of node configurations. For example, each of the node members can extend from its respective interface surface such that the contact surfaces are disposed between the interface surfaces prior to deployment, one of the node members can extend from its interface surface such that the contact surfaces are substantially flush with the other interface surface prior to deployment, or one of the node members can extend from one interface surface and the other node member can be recessed relative to the other interface surface such that the contact surfaces are outside of the area between the interface surfaces prior to deployment. In the last of these cases, it will be appreciated that the depth of the recessed node member will generally be less than the height of the extended node member so that the interface surfaces may remain separated.
According to another aspect of the present invention, an interface apparatus is provided that includes structure for bearing lateral loads. In a variety of deployable unit applications including, for example, dispensing payload spacecraft into orbit from a launch vehicle, substantial lateral loads may be experienced at the separation plane. Such loads may result, for example, from vibrations as the launch vehicle is launched and travels through the Earth""s atmosphere. Such loads can generate substantial shear at the separation plane, potentially resulting in unintended separation if not adequately supported. In accordance with the present invention, a separation apparatus includes a support structure node member and a deployable unit node member including contact surfaces defining a separation plane. The apparatus further includes a lateral load bearing element associated with the contact surfaces at the separation plane for bearing loads having a component aligned with the separation plane so as to reduce the likelihood of unintended shearing separation prior to planned deployment. The lateral load bearing element preferably includes structure extending across the separation plane at the contact surfaces. Such structure may be provided by forming the contact surfaces of the node members in a non-planar configuration or by otherwise providing structure extending across the separation plane at the interface between the contact surfaces. In one embodiment, one of the contact surfaces includes a tongue and the other contact surface includes a mating groove such that the resulting tongue-in-groove structure provides resistance to shear forces.
According to a further aspect of the invention, an apparatus is provided for integrating the separation assembly and interface structure in connection with a deployment system. The apparatus includes a support structure node member, a deployable unit node member and a separation bolt assembly. The bolt assembly has a first portion connected to the support structure node member and a second portion connected to the deployable unit node member. The bolt assembly is separable between the first and second portions to effect deployment. Preferably, the bolt assembly includes an elongate element extending from one of the node members to the other across the separation plane there between. In one embodiment, the node members define an internal passageway extending between the node members and the separation bolt assembly extends within the passageway. By virtue of such structure, the separation and interface functionality is integrated into a single unit that can be standardized for use in connection with different types of support structure/deployable unit interfaces.
According to a still further aspect of the present invention, a biasing assembly is provided in combination with interface node members to facilitate deployable unit separation. The associated apparatus comprises a support structure node member and a deployable unit node member including contact surfaces defining a separation plane. The apparatus further includes a biasing assembly connected to at least one of the deployable unit and support structure, for urging the contact surfaces apart so as to facilitate deployment of the deployable unit. The biasing assembly, which may include a spring or any other mechanism suitable for exerting a separation force, may act on one or both of the node members or directly on the support structure and/or deployable unit. In a preferred embodiment, the biasing assembly is interconnected to one of the nodes and bears against the other of the nodes in order to provide the desired biasing.